Zoom lens and image-pickup apparatus including the same

ABSTRACT

The zoom lens includes a front unit including a first positive lens unit and a second positive or negative lens unit, a reflective mirror and a rear unit including two or more lens units. During zooming, the reflective mirror is not moved, and the first lens unit and at least two lens units of the rear unit are moved. When the zoom lens is retracted into a body of an image pickup apparatus, at least one of rotation of the reflective mirror such that a normal line thereto is brought closer to parallel to an optical axis of the rear unit and axial movement thereof in a direction of the optical axis of the rear unit is performed. The front unit is moved into a space formed by the at least one of the rotation and the axial movement. Conditions of 10.5&lt;ft/|fn|&lt;30.0 and 0.80&lt;(Lf−L)/Lm&lt;1.30 are satisfied.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a compact zoom lens having a high zoomratio and suitable for image pickup apparatuses such as digital stillcameras and video cameras.

2. Description of the Related Art

Image capturing optical systems used for image pickup apparatuses(cameras) are required to be compact as a whole, capable of reducing athickness of the camera and configured as a zoom lens having a high zoomratio.

There is known a retractable zoom lens which reduces distances amongmutually adjacent lens units in a non-image capturing state to differentdistances from those thereamong in an image capturing state, whereby thelens units are retracted inside a camera body. There is also known aso-called bent zoom lens in which a reflective mirror that bends anoptical axis of the image capturing optical system by 90 degrees isdisposed in its optical path. There is further known a bent zoom lensthat bends its optical path by using the reflective mirror in the imagecapturing state and that rotates the reflective mirror in the non-imagecapturing state to retract an object-side lens unit in a space formed bythe rotation of the reflective mirror.

Japanese Patent Application Laid-open No. 2007-279541 discloses a bentzoom lens in which a reflective mirror is disposed between a second lensunit and a third lens unit counted from an object side and which rotatesthe reflective mirror in the non-image capturing state to retract afront unit on the object side further than the reflective mirror in aspace formed by the rotation of the reflective mirror.

U.S. Pat. No. 7,630,142 discloses a zoom lens in which a reflectivemirror between a third lens unit and a fourth lens unit counted from anobject side and which rotates the reflective mirror in the non-imagecapturing state to retract a front unit on the object side further thanthe reflective mirror in a space formed by the rotation of thereflective mirror.

Furthermore, there is known a bent-retractable zoom lens which moves inthe non-image capturing state a reflective mirror to a space differentfrom that in the image capturing state, whereby a lens unit on an objectside further than the reflective mirror is retracted.

U.S. Pat. No. 7,692,869 discloses a zoom lens in which a reflectivemirror is disposed between a second lens unit and a third lens unitcounted from an object side and which moves the reflective mirror and alens unit disposed on an image side further than the reflective mirrorto retract an object-side lens unit in a space formed by the movementthereof.

Such zoom lenses provided with the reflective mirror which bends theoptical path of the image capturing optical system are likely tosimultaneously realize a high zoom ratio and thinning of a camera.However, in order to achieve these advantages, it is important toappropriately set a lens configuration of the zoom lens, arrangement ofthe reflective mirror in the optical path, configurations of therespective lens units on the object and image sides further than thereflective mirror and others.

SUMMARY OF THE INVENTION

The present invention provides a zoom lens having a high zoom ratio andcapable of reducing a thickness of an image pickup apparatus providedwith the zoom lens.

The present invention provides as one aspect thereof a zoom lensincluding in order from an object side to an image side, a front unitincluding a first lens unit having a positive refractive power and asecond lens unit having a positive or negative refractive power, areflective mirror which bends an optical path from the front unit, and arear unit including two or more lens units. During zooming, thereflective mirror is not moved, and the first lens unit and at least twolens units included in the two or more lens units of the rear unit aremoved in directions of optical axes of the front and rear units,respectively. When the zoom lens is retracted into a body of the imagepickup apparatus, at least one of rotation of the reflective mirror suchthat a normal line to a reflective surface of the reflective mirror isbrought closer to parallel to the optical axis of the rear unit andaxial movement of the reflective mirror in the direction of the opticalaxis of the rear unit is performed, and at least part of the front unitis moved into a space formed by the at least one of the rotation and theaxial movement of the reflective mirror. The following conditions aresatisfied:10.5<ft/|fn|<30.00.80<(Lf−L)/Lm<1.30where fn represents a focal length of a strongest negative power lensunit having a negative refractive power whose absolute value is maximumamong those lens units each having a negative refractive power andincluded in the front unit, ft represents a focal length of the entirezoom lens at a telephoto end, Lm represents a length of the reflectivemirror in a sectional plane including the optical axes of the front andrear units, Lf represents a sum of optical-axis-directional thicknessesof respective lens units included in the front unit, and L represents ashorter one of lengths in the direction of the optical axis of the frontunit from an apex of a most-object side lens surface of the first lensunit to ends of the reflective mirror in the sectional plane after thezoom lens is retracted in the body of the image pickup apparatus.

The present invention provides another aspect thereof an image pickupapparatus including a body of the image pickup apparatus, the above zoomlens, and an image sensor which receives an image formed by the zoomlens.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a zoom lens that is Embodiment 1 of thepresent invention at a wide-angle end, whose optical path is developedat a reflective mirror.

FIGS. 2A and 2B are aberration charts of the zoom lens of Embodiment 1at the wide-angle end and at a telephoto end, respectively.

FIGS. 3A and 3B show the zoom lens of Embodiment 1 in an image capturingstate and in a retracted state, respectively.

FIG. 4 is a sectional view of a zoom lens that is Embodiment 2 of thepresent invention at a wide-angle end, whose optical path is developedat a reflective mirror.

FIGS. 5A and 5B are aberration charts of the zoom lens of Embodiment 2at the wide-angle end and at a telephoto end, respectively.

FIG. 6 shows the zoom lens of Embodiment 2 in a retracted state.

FIG. 7 is a sectional view of a zoom lens that is Embodiment 3 of thepresent invention at a wide-angle end, whose optical path is developedat a reflective mirror.

FIGS. 8A and 8B are aberration charts of the zoom lens of Embodiment 3at the wide-angle end and at a telephoto end, respectively.

FIG. 9 shows the zoom lens of Embodiment 3 in a retracted state.

FIG. 10 is a sectional view of a zoom lens that is Embodiment 4 of thepresent invention at a wide-angle end, whose optical path is developedat a reflective mirror.

FIGS. 11A and 11B are aberration charts of the zoom lens of Embodiment 4at the wide-angle end and at a telephoto end, respectively.

FIG. 12 shows the zoom lens of Embodiment 4 in a retracted state.

FIG. 13 is a sectional view of a zoom lens that is Embodiment 5 of thepresent invention at a wide-angle end, whose optical path is developedat a reflective mirror.

FIGS. 14A and 14B are aberration charts of the zoom lens of Embodiment 5at the wide-angle end and at a telephoto end, respectively.

FIG. 15 shows the zoom lens of Embodiment 5 in a retracted state.

DESCRIPTION OF THE EMBODIMENTS

Exemplary embodiments of the present invention will hereinafter bedescribed with reference to the accompanying drawings.

A zoom lens of each embodiment of the present invention is constitutedby, in order from an object side to an image side, a front unitincluding a first lens unit having a positive refractive power and asecond lens unit having a positive or negative refractive power, areflective mirror which bends an optical path from the front unit, and arear unit including two or more lens units. During zooming, thereflective mirror is not moved, while the first lens unit and at leasttwo lens units included in the two or more lens units of the rear unitare moved in directions of optical axes of the front and rear units,respectively.

When the zoom lens is retracted into a body of an image pickup apparatus(hereinafter referred to as “a camera body”), at least one of rotationof the reflective mirror about a rotation axis and axial movement of thereflective mirror in the direction of the optical axis of the rear unitis performed. At least part of the front unit is moved into a spaceformed by the at least one of the rotation and the axial movement of thereflective mirror.

FIG. 1 shows a configuration of a zoom lens of a first embodiment(Embodiment 1) of the present invention at a wide-angle end (short focallength end). FIGS. 2A and 2B show various aberrations of the zoom lensof Embodiment 1 at the wide-angle end and at a telephoto end (long focallength end), respectively. FIG. 3A shows a configuration of the zoomlens of Embodiment 1 in an image capturing state, the optical path ofthe zoom lens being bent at the reflective mirror. FIG. 3B shows aconfiguration of the zoom lens of Embodiment 1 in a non-image capturingstate, the zoom lens being retracted in the camera body.

FIG. 4 shows a configuration of a zoom lens of a second embodiment(Embodiment 2) of the present invention at a wide-angle end, an opticalpath of the zoom lens being developed at a reflective mirror. FIGS. 5Aand 5B show various aberrations of the zoom lens of Embodiment 2 at thewide-angle end and at a telephoto end, respectively. FIG. 6 shows aconfiguration of the zoom lens of Embodiment 2 in a non-image capturingstate, the zoom lens being retracted in the camera body.

FIG. 7 shows a configuration of a zoom lens of a third embodiment(Embodiment 3) of the present invention at a wide-angle end. FIGS. 8Aand 8B show various aberrations of the zoom lens of Embodiment 3 at thewide-angle end and at a telephoto end, respectively. FIG. 9 shows aconfiguration of the zoom lens of Embodiment 3 in a non-image capturingstate, the zoom lens being retracted in the camera body.

FIG. 10 shows a configuration of a zoom lens of a fourth embodiment(Embodiment 4) of the present invention at a wide-angle end. FIGS. 11Aand 11B show various aberrations of the zoom lens of Embodiment 4 at thewide-angle end and at a telephoto end, respectively. FIG. 12 shows aconfiguration of the zoom lens of Embodiment 4 in a non-image capturingstate, the zoom lens being retracted in the camera body.

FIG. 13 shows a configuration of a zoom lens of a fifth embodiment(Embodiment 5) of the present invention at a wide-angle end. FIGS. 14Aand 14B show various aberrations of the zoom lens of Embodiment 5 at thewide-angle end and at a telephoto end, respectively. FIG. 15 shows aconfiguration of the zoom lens of Embodiment 5 in a non-image capturingstate, the zoom lens being retracted in the camera body.

Although an optical path of the actual zoom lens of each embodiment isbent by the reflective mirror, FIGS. 1, 4, 7, 10 and 13 each show theconfiguration of the zoom lens whose optical path is developed at thereflective mirror.

The zoom lens of each embodiment is used as an image capturing lensprovided in image pickup apparatuses (hereinafter each referred to as “acamera”) such as video cameras, digital still cameras and silver-haloidfilm cameras. In each figure showing the configuration of the zoom lens,a left side corresponds to the object side (front side), and a rightside corresponds to the image side (rear side). Moreover, LF denotes thefront unit including the first lens unit and the second lens unit, URdenotes the reflective mirror that bends the optical path by 90 degreesor approximately 90 degrees, and LR denotes the rear unit including thetwo or more lens units.

Furthermore, i represents a number counted from the object side, and Lirepresents an i-th lens unit. SP represents an aperture stop that limitsan F-number, G represents an optical block such as an optical filter, aface plate, a quartz low-pass filter and an infrared cutting filter.

In addition, IP represents an image plane. An image pickup plane of animage sensor (photoelectric conversion element) such as a CCD sensor ora CMOS sensor is disposed at the image plane IP when the zoom lens isused as the image capturing lens for video cameras or digital stillcameras. A film surface is placed at the image plane IP when the zoomlens is used as the image capturing lens for silver-haloid film cameras.

Arrows show movement loci of the respective lens units in zooming fromthe wide-angle end to the telephoto end. An arrow IS represents amovement direction of a lens unit when image blur due to shaking of thecamera is corrected.

FIGS. 2A, 2B, 5A, 5B, 8A, 8B, 11A, 11B, 14A and 15A each show sphericalaberration for a d-line, spherical aberration for a g-line, astigmatismΔM in a meridional image plane, astigmatism ΔS in a sagittal imageplane, distortion, and chromatic aberration of magnification for theg-line. In these figure, co represents a half angle of view (half of animage capturing field angle), and Fno represents an F-number. In eachembodiment, the wide-angle end and the telephoto end are zoom positionswhere a lens unit (or lens units) for variation of magnification islocated at mechanical ends of its movable range in the direction of theoptical axis (hereinafter referred to as “an optical axis direction”).

In the zoom lens of each embodiment, the front unit LF includes, inorder from the object side to the image side, the first lens unit L1having a positive refractive power and the second lens unit L2 having apositive or negative refractive power. The rear unit LR includes two ormore lens units. During zooming, the reflective mirror UR is not moved,while the first lens unit L1 and at least two lens units included in thetwo or more lens units of the rear unit LR are moved in the optical axisdirection. Providing The reflection member UR which bends the light fromthe object side in the optical path reduces a thickness of the camera.

Moreover, in each embodiment, using the reflective mirror UR, not areflective prism, as a reflective member to bend the optical pathenables reducing width of the camera in a state where the zoom lens isretracted (hereinafter referred to as “a lens retracted state”) sincethe reflective mirror UR can be disposed so as not to occupy a largespace in the optical axis direction of the rear unit LR in the lensretracted state. In the lens retracted state, the reflective mirror URis disposed after its rotation such that a normal line to its reflectivesurface (hereinafter referred to as “a reflective surface normal line”)is approximately parallel to the optical axis of the rear unit LR. Withthe use of the reflective mirror UR, reducing magnification varyingstrokes of the lens units of the rear unit LR which are moved duringzooming makes it possible to optically reduce the camera width. Sincethe magnification varying strokes of the lens units of the rear unit LRare reduced, a focal length of a lens unit having a negative refractivepower whose absolute value is maximum among those of lens units includedin the front unit LF disposed on the object side further than thereflective mirror UR is appropriately set so as to reduce a front lensdiameter and to facilitate achievement of a desired zoom ratio.

Next, description will be made of the configuration of the zoom lens inthe lens retracted state with reference to FIGS. 3A and 3B, by takingEmbodiment 1 as an example. When the zoom lens is retracted into thecamera body, the reflective mirror UR and the rear unit LR are moved tothe image side, and the reflective mirror UR is further rotated aboutits rotation center (a rotation axis rotatably supporting the reflectivemirror UR) such that the reflective surface normal line thereof isbrought closer to parallel to the optical axis of the rear unit LR. Thereflective mirror UR may be rotated about the rotation center after themovement to the image side, and may be moved to the image side after therotation. Such rotation and movement of the reflective mirror UR and therear unit LR enables retraction of part (one or more lens units) of thefirst unit LF in a partial space formed thereby in a direction of thecamera width in the lens retracted state. Furthermore, since thereflective mirror UR is rotated and moved away from its position in theimage capturing state to form the space where the part of the first unitLF is retracted, the thickness of the camera is reduced.

Although in FIGS. 3A and 3B both the rotation of the reflective mirrorUR about the rotation axis and the movement (hereinafter referred to as“axial movement”) of the reflective mirror UR in a direction parallel tothe optical axis of the rear unit LR are performed when the zoom lens isretracted, it is only necessary that at least one of the rotation andthe axial movement thereof be performed. For example, the reflectivemirror UR may be rotated about the rotation axis to be retracted suchthat the reflective surface normal line is brought parallel to theoptical axis of the front unit LF. Furthermore, the reflective mirror URmay be retracted in other ways than the above-mentioned ones; forexample, the reflective mirror UR may be moved perpendicularly to apaper of FIGS. 3A and 3B without being moved to the image side such thatthe reflective surface normal line is brought approximatelyperpendicular to the optical axis of the front unit LF.

In each embodiment, the front unit LF is disposed on the object sidefurther than the reflective mirror UR, and the rear unit LR is disposedon the image side further than the reflective mirror UR. The reflectivemirror UR bends the optical axis from the front unit LF by approximate90° (90±10°) to connect it to the optical axis of the rear unit LR.

In the lens retracted state shown in FIGS. 3B, 6, 9 and 12, thereflective surface normal line of the reflective mirror UR and theoptical axis of the rear unit LR form an angle of 0°. In the lensretracted state shown in FIG. 15, the reflective surface normal line ofthe reflective mirror UR and the optical axis of the rear unit LR forman angle of 10°. The angle formed by the reflective surface normal lineof the reflective mirror UR and the optical axis of the rear unit LR maybe larger than 0° to some degree.

In the following description, fn represents a focal length of theabove-mentioned lens unit (also referred to as “a strongest negativepower lens unit”) having the negative refractive power whose absolutevalue is maximum among those lens units each having a negativerefractive power and included in the front unit LF, and ft represents afocal length of the entire zoom lens at the telephoto end. Moreover, Lmrepresents a length of the reflective mirror in a sectional plane(longitudinal sectional plane shown in FIGS. 3A and 3B) including theoptical axes of the front and rear units LF and LR, and Lf represents asum of optical-axis-directional thicknesses of the respective lens unitsincluded in the front unit LF. Furthermore, as shown in FIG. 3B, Lrepresents a shorter one of lengths in the optical axis direction of thefront unit LF from an apex of a most-object side lens surface of thefirst lens unit L1 to ends of the reflective mirror UR in the sectionalplane after the zoom lens is retracted in the camera body (in the lensretracted state) as shown in FIG. 3B.

In each embodiment, the following conditions are satisfied:10.5<ft/|fn|<30.0  (1)0.80<(Lf−L)/Lm<1.30  (2).

The zoom lens in each embodiment is a positive-lead zoom lens in which amost-object side lens unit is a positive lens unit having a positiverefractive power. The reflective mirror UR is not moved and the firstlens unit L1 and the at least two lens units of the rear unit LR aremoved, which achieves a high zoom ratio. Moreover, in the lens retractedstate, the part of the front unit LF is retracted in the space formed byat least one of the rotation and axial movement of the reflective mirrorUR, which achieves thinning of the camera.

Condition (1) limits a ratio of the focal length ft of the entire zoomlens at the telephoto end to the focal length (absolute value) fn of thestrongest negative power lens unit of the front unit LF. A lower valueof ft/|fn| than the lower limit of condition (1) excessively reduces therefractive power of the strongest negative power lens unit, which makesit difficult to achieve a high zoom ratio. A higher value of ft/|fn|than the upper limit of condition (1) excessively increases therefractive power of the strongest negative power lens unit, whichparticularly increases a thickness of an edge portion of each negativelens of the strongest negative power lens unit and thereby makes itdifficult to reduce the camera thickness.

Condition (2) limits a relation among a total thickness of lensthicknesses of the respective lens units included in the front unit LF(each lens thickness is a length from an object side lens surface to animage side lens surface of each lens unit), a size of the reflectivemirror UR and location of the reflective mirror UR. The size of thereflective mirror UR highly influences the camera thickness. A longlength of the reflective mirror UR making a value of (Lf−L)/Lm lowerthan the lower limit of condition (2) increases the magnificationvarying movement stroke of the lens units included in the front unit LF,which increases the total length of the zoom lens and thereby increasesthe camera thickness. On the other hand, a higher value of (Lf−L)/Lmthan the upper limit of condition (2) increases the total thickness ofthe front unit LF with respect to the size of the reflective mirror UR,which undesirably increases the camera thickness.

It is desirable to set the numerical ranges of conditions (1) and (2) asfollows to achieve a more compact camera:12.0<ft/|fn|<20.0  (1a)0.85<(Lf−L)/Lm<1.20  (2a).

As described above, each embodiment satisfies the above conditions andthereby achieves a compact zoom lens having a high zoom ratio. Moreover,it is desirable to satisfy at least one of the following conditionswhere fr represents a focal length of a most-image side lens unitdisposed at a most-image side position among the lens units included inthe rear unit LR, Nn represents an average refractive index of materialsof two or more negative lenses included in the strongest negative powerlens unit of the front unit LF, Zf represents a variable magnificationratio of the front unit LF, Zr represents a variable magnification ratioof the rear unit LR, and α represents an angle formed between thereflective surface normal line of the reflective mirror UR and theoptical axis of the rear unit LR in the lens retracted state (that is,after the zoom lens is retracted in the camera body).0.10<fr/ft<0.40  (3)1.85<Nn<2.00  (4)1.50<Zf/Zr<6.00  (5)|α|<15°  (6).

Description will be made of technical meanings of each of conditions (3)to (6).

Condition (3) limits the focal length of the most-image side lens unit(final lens unit). The focal length of the final lens unit making avalue of fr/ft lower than the lower limit of condition (3) increases arefractive power and an effective diameter of the final lens unit, whichincreases the camera thickness. On the other hand, a higher value offr/ft than the upper limit of condition (3) makes it difficult to securea sufficient variable magnification ratio by the rear unit LR, whichincreases a magnification varying burden of the lens units disposed onthe object side further than the reflective mirror UR and increasesmovement amounts thereof, resulting in increase of the camera thickness.

Condition (4) limits the average refractive index of the materials ofthe two or more negative lenses included in the strongest negative powerlens unit of the front unit LF. A lower value of Nn than the lower limitof condition (4) increases the edge portion of each negative lens, whichincreases the camera thickness. On the other hand, a higher value of Nnthan the upper limit of condition (4) generally makes it necessary touse a high dispersion material, which makes it difficult to correctchromatic aberration and thereby makes the lens configurationcomplicated, resulting in increase in size of the camera.

Condition (5) limits a ratio of the variable magnification ratio of therear unit LR to that of the front unit LF. A lower value of Zf/Zr thanthe lower limit of condition (5) excessively decreases a magnificationvarying burden of the front unit LF, which increases the camera width.On the other hand, a higher value of Zf/Zr than the upper limit ofcondition (5) excessively increases the magnification varying burden ofthe front unit LF, which makes it difficult to reduce the camerathickness.

Condition (6) limits the angle between the reflective surface normalline of the reflective mirror UR and the optical axis of the rear unitLR in the lens retracted state. A higher value of |α| than 15° increasesthe space occupied by the reflective mirror UR in the camera widthdirection in the lens retracted state, which undesirably increases thesize of the camera.

It is more desirable to set the numerical ranges of conditions (3) to(6) as follows:0.10<fr/ft<0.33  (3a)1.85<Nn<1.95  (4a)1.50<Zf/Zr<5.50  (5a)|α|<12°  (6a).

In each embodiment, as shown in FIGS. 3B, 6, 9, 12 and 15, when the zoomlens is retracted into the camera body, the reflective mirror UR isrotated about the rotation axis which rotatably supports the reflectivemirror UR and is moved to the image side and thereby forms the spacewhere the part of the front unit LF is retracted. This configurationenables, in the camera width direction, effective utilization of a spaceoccupied by the reflective mirror UR in the image capturing state as thespace for retracting the front unit LF in the lens retracted state. Asmentioned above, at least one of the rotation and the perpendicularmovement to the optical axis of the front unit LF (that is, the axialmovement parallel to the optical axis of the rear unit LR) of thereflective mirror UR may be performed when the zoom lens is retractedinto the camera body. At least one of the rotation and the perpendicularmovement also enables effective utilization of the space occupied by thereflective mirror UR in the image capturing state as the space forretracting the front unit LF in the lens retracted state.

In each embodiment, one lens unit included in the rear unit LR includesin order from the object side to the image side a first sub-lens unitand a second sub-lens unit which is moved in a direction including avertical direction component to the optical axis of the rear unit LR formoving an imaging position in directions orthogonal to the optical axis.

Some zoom lenses including a reflective mirror and having a high zoomratio employ a configuration that moves movable lens units toward thereflective mirror in zooming from a wide-angle end to a telephoto end.In such a configuration, dividing any one of lens unit included in arear unit LR into multiple partial lens units (sub-lens units) andmoving an image-side sub lens unit thereamong in a direction including avertical direction component to an optical axis of the rear unit LRfacilitates correction of image blur due to shaking of the zoom lens(camera) while preventing interference of the lens units particularly atthe telephoto end.

Next, description will be made of the lens configuration of eachembodiment.

Embodiment 1

In the zoom lens of Embodiment 1 shown in FIG. 1, the front unit LF isconstituted by, in order from the object side to the image side, thefirst lens unit L1 having the positive refractive power and the secondlens unit L2 having the negative refractive power. The rear unit LR isconstituted by, in order from the object side to the image side, a thirdlens unit L3 having a positive refractive power, a fourth lens unit L4having a negative refractive power and a fifth lens unit L5 having apositive refractive power. The reflective mirror UR is disposed betweenthe second lens unit L2 and the third lens unit L3.

During zooming from the wide-angle end to the telephoto end, the secondlens unit L2, the reflective mirror UR and the fourth lens unit L4 arenot moved. The first lens unit L1 is linearly moved to the object sideor is moved so as to draw a locus convex toward the image side. Thethird lens unit L3 is moved to the object side. The fifth lens unit L5is non-linearly moved to the image side in order to correct variation ofthe image plane IP with variation of magnification.

The zoom lens of this embodiment fixes the reflective mirror UR, thesecond lens unit L2 and the fourth lens unit L4 and moves the first lensunit L1, the third lens unit L3 and the fifth lens unit L5 during thezooming to achieve a high zoom ratio of approximately 13. The zoom lensof this embodiment moves the fifth lens unit L5 for focusing.

In this embodiment, the third lens unit L3 includes a first sub-lensunit L3 a and a second sub-lens unit L3 b; the second sub-lens unit L3 bis moved in the directions orthogonal to the optical axis for correctingimage blur due to the shaking of the zoom lens.

Embodiment 2

In the zoom lens of Embodiment 2 shown in FIG. 4, the front unit LF isconstituted by, in order from the object side to the image side, thefirst lens unit L1 having the positive refractive power, the second lensunit L2 having the negative refractive power and a third lens unit L3having a negative refractive power. The rear unit LR is constituted by,in order from the object side to the image side, a fourth lens unit L4having a positive refractive power, a fifth lens unit L5 having anegative refractive power and a sixth lens unit L6 having a positiverefractive power. The reflective mirror UR is disposed between the thirdlens unit L3 and the fourth lens unit L4.

During zooming from the wide-angle end to the telephoto end, the thirdlens unit L3, the reflective mirror UR and the fifth lens unit L5 arenot moved. The first lens unit L1 is linearly moved to the object sideor is moved so as to draw a locus convex toward the image side. Thesecond lens unit L2 is moved so as to draw a locus convex toward theimage side. The fourth lens unit L4 is moved to the object side. Thesixth lens unit L6 is moved so as to draw a locus convex toward theobject side. The zoom lens of this embodiment thus fixes the reflectivemirror UR, the third lens unit L3 and the fifth lens unit L5 and movesthe first lens unit L1, the second lens unit L2, the fourth lens unit L4and the sixth lens unit L6 during the zooming to achieve a high zoomratio of approximately 15. The zoom lens of this embodiment moves thesixth lens unit L6 for focusing.

In this embodiment, the fourth lens unit L4 includes a first sub-lensunit L4 a and a second sub-lens unit L4 b; the second sub-lens unit L4 bis moved in the directions orthogonal to the optical axis for correctingimage blur due to the shaking of the zoom lens. Other configurations areidentical to those in Embodiment 1.

Embodiment 3

In the zoom lens of Embodiment 3 shown in FIG. 7, the front unit LF isconstituted by, in order from the object side to the image side, thefirst lens unit L1 having the positive refractive power and the secondlens unit L2 having the negative refractive power. The rear unit LR isconstituted by, in order from the object side to the image side, a thirdlens unit L3 having a negative refractive power, a fourth lens unit L4having a positive refractive power, a fifth lens unit L5 having anegative refractive power and a sixth lens unit L6 having a positiverefractive power. The reflective mirror UR is disposed between thesecond lens unit L2 and the third lens unit L3.

During zooming from the wide-angle end to the telephoto end, thereflective mirror UR, the third lens unit L3 and the fifth lens unit L5are not moved. The first lens unit L1, the second lens unit L2, thefourth lens unit L4 and the sixth lens unit L6 are moved similarly tothose in Embodiment 2. The zoom lens of this embodiment thus fixes thereflective mirror UR, the third lens unit L3 and the fifth lens unit L5and moves the first lens unit L1, the second lens unit L2, the fourthlens unit L4 and the sixth lens unit L6 during the zooming to achieve ahigh zoom ratio of approximately 15. The zoom lens of this embodimentmoves the sixth lens unit L6 for focusing.

In this embodiment, the fourth lens unit L4 includes a first sub-lensunit L4 a and a second sub-lens unit L4 b; the second sub-lens unit L4 bis moved in the directions orthogonal to the optical axis for correctingimage blur due to the shaking of the zoom lens. Other configurations areidentical to those in Embodiment 1.

Embodiment 4

In the zoom lens of Embodiment 4 shown in FIG. 10, the front unit LF isconstituted by, in order from the object side to the image side, thefirst lens unit L1 having the positive refractive power and the secondlens unit L2 having the negative refractive power. The rear unit LR isconstituted by, in order from the object side to the image side, a thirdlens unit L3 having a positive refractive power and a fourth lens unitL4 having a positive refractive power. The reflective mirror UR isdisposed between the second lens unit L2 and the third lens unit L3.

During zooming from the wide-angle end to the telephoto end, thereflective mirror UR is not moved. The first lens unit L1 is linearlymoved to the object side or is moved so as to draw a locus convex towardthe image side. The second lens unit L2 is moved so as to draw a locusconvex toward the image side. The third lens unit L3 is moved to theobject side. The fourth lens unit L4 is moved so as to draw a locusconvex toward the object side. The zoom lens of this embodiment thusfixes the reflective mirror UR and moves the first lens unit L1, thesecond lens unit L2, the third lens unit L3 and the fourth lens unit L4during the zooming to achieve a high zoom ratio of approximately 16. Thezoom lens of this embodiment moves the fourth lens unit L4 for focusing.

In this embodiment, the third lens unit L3 includes a first sub-lensunit L3 a and a second sub-lens unit L3 b; the second sub-lens unit L3 bis moved in the directions orthogonal to the optical axis for correctingimage blur due to the shaking of the zoom lens. Other configurations areidentical to those in Embodiment 1.

Embodiment 5

In the zoom lens of Embodiment 5 shown in FIG. 13, the front unit LF isconstituted by, in order from the object side to the image side, thefirst lens unit L1 having the positive refractive power, the second lensunit L2 having the positive refractive power and a third lens unit L3having a negative refractive power. The rear unit LR is constituted by,in order from the object side to the image side, a fourth lens unit L4having a positive refractive power, a fifth lens unit L5 having anegative refractive power and a sixth lens unit L6 having a positiverefractive power. The reflective mirror UR is disposed between the thirdlens unit L3 and the fourth lens unit L4.

During zooming from the wide-angle end to the telephoto end, the thirdlens unit L3 and the reflective mirror UR are not moved. The first lensunit L1, the second lens unit L2 and the fourth lens unit L4 are movedto the object side. The fifth lens unit L5 is moved so as to draw alocus convex toward the image side. The sixth lens unit L6 is moved asto draw a locus convex toward the object side. The zoom lens of thisembodiment thus fixes the reflective mirror UR and the third lens unitL3 and moves the first lens unit L1, the second lens unit L2, the fourthlens unit L4, the fifth lens unit L5 and the sixth lens unit L6 duringthe zooming to achieve a high zoom ratio of approximately 16. The zoomlens of this embodiment moves the sixth lens unit L6 for focusing.

In this embodiment, the fourth lens unit L4 includes a first sub-lensunit L4 a and a second sub-lens unit L4 b; the second sub-lens unit L4 bis moved in the directions orthogonal to the optical axis for correctingimage blur due to the shaking of the zoom lens. Other configurations areidentical to those in Embodiment 1.

The zoom lens configurations of Embodiments 1 to 5 are merely examples,and therefore other zoom lens configurations may be employed. In eachembodiment, an aperture diameter of the aperture stop SP may becontrolled to reduce variation of the F-number with the zooming.Moreover, distortion aberration may be electrically corrected when thezoom lens is used in an image pickup apparatus provided with an imagesensor that photoelectrically converts an object image formed on itslight-receiving surface by the zoom lens.

Specific numerical data of Numerical Examples 1 to 5 respectivelycorresponding to Embodiments 1 to 5 are shown below. In the data, idenotes a number of each surface counted from the object side, ridenotes a curvature radius of the i-th surface (optical surface), didenotes an axial distance between the i-th surface and an (i+1)-thsurface, and ndi and νdi respectively denote a refractive index and anAbbe number of a material of an i-th optical element for the d-line. Anaspheric shape is expressed by the following expression where krepresents an

eccentricity, x represents a displacement amount from a surface apex inthe optical axis direction at a height h from an optical axis, Rrepresent a paraxial curvature radius, and A4, A6, A8 and A10 representaspheric coefficients.x=(h ² /R)/{1+[1−(1+k)×(h/R)²]^(1/2) }+A4×h ⁴ +A6×h ⁶ +A8×h ⁸ +A10×h ¹⁰

In addition, “E±Z” in each aspheric coefficient means “×10±Z”. In thedata, the last two surfaces are object-side and image-side surfaces ofthe optical block such as a filter and a face plate. Moreover, a backfocus (BF) represents a distance from the image-side surface (finalsurface) of the optical block to the image plane. A total lens length isa distance from the most-object side surface to the final surface addedwith the back focus. Table 1 shows relations between the above-describedconditions and Numerical Examples 1 to 5.

Numerical Example 1

Unit mm Surface data Surface Effective No. r d nd νd diameter  1 36.2801.10 1.84666 23.8 27.32  2 22.075 5.00 1.49700 81.5 25.18  3 3819.4840.10 24.91  4 21.953 3.40 1.71300 53.9 23.62  5 83.784 (Variable) 23.08 6 67.363 1.05 1.84954 40.1 12.55  7* 7.239 2.86 9.23  8 −11.608 0.601.88300 40.8 8.77  9 8.601 0.19 8.49 10 9.629 2.04 1.94595 18.0 8.57 11−92.242 4.80 8.51 12 ∞ (Variable) 11.31 13* 8.197 2.52 1.55332 71.7 7.4414* −83.098 1.00 6.92 15(SP) ∞ 1.00 6.31 16 9.731 0.60 1.84666 23.8 6.3217 6.137 1.40 6.05 18 10.932 3.42 1.54814 45.8 6.63 19 −10.241 0.601.80610 33.3 6.53 20 −44.165 (Variable) 6.65 21 −16.021 0.70 1.7725049.6 7.60 22 232.382 (Variable) 7.91 23* 14.352 3.61 1.48749 70.2 11.0524 −13.063 (Variable) 11.19 25 ∞ 0.80 1.51633 64.1 20.00 26 ∞ 2.37 20.00IP ∞ Aspheric surface data 7th surface K = −2.66260e−001 A 4 =1.25506e−004 A 6 = −1.40891e−005 A 8 = 1.00423e−006 A10 = −2.39914e−00813th surface K = −2.33750e−001 A 4 = −3.57071e−005 A 6 = −1.50723e−006 A8 = 1.80588e−008 14th surface K = 0.00000e+000 A 4 = 4.19704e−005 23thsurface K = 0.00000e+000 A 4 = −2.08667e−004 A 6 = 1.38190e−006 A 8 =−2.20568e−008 Various data zoom ratio 12.75 Wide Middle Tele focallength 5.18 22.00 66.05 F-number 3.07 4.67 6.42 half angle of view (°)33.59 8.89 2.98 Image height 3.44 3.44 3.44 Total lens length 72.0882.71 88.34 BF 2.37 2.37 2.37 d 5 0.50 11.14 16.87 d12 18.28 6.91 4.30d20 1.36 12.73 15.29 d22 4.68 5.05 10.75 d24 8.10 7.72 1.97 Entrancepupil 17.46 59.48 143.60 Exit pupil −61.28 152.44 38.52 Front principalpoint 22.22 84.71 330.31 Rear principal point −2.81 −19.63 −63.68 Zoomlens unit data Front Rear Lens Start Focal Unit principal principal unitsurface length length point point 1 1 32.00 9.59 2.33 −3.75 2 6 −5.4111.54 1.45 −8.21 3 13 14.26 10.55 0.39 −7.75 4 21 −19.38 0.70 0.03 −0.375 23 14.66 3.61 1.33 −1.21 GB 25 ∞ 0.80 0.26 −0.26 Lens element datalens Start surface Focal length 1 1 −69.04 2 2 44.66 3 4 40.79 4 6 −9.625 8 −5.52 6 10 9.31 7 13 13.62 8 16 −21.25 9 18 10.23 10 19 −16.67 11 21−19.38 12 23 14.66 13 25 0.00

Numerical Example 2

Unit mm Surface data Surface Effective No. r d nd νd diameter  1 34.2881.10 1.84666 23.8 26.50  2 20.047 4.76 1.49700 81.5 24.13  3 157.8490.10 23.92  4 22.449 3.42 1.77250 49.6 23.37  5 106.336 (Variable) 22.91 6 102.105 1.05 1.84954 40.1 14.07  7* 7.207 3.24 10.15  8 −17.054 0.601.88300 40.8 9.85  9 10.643 0.10 9.63 10 10.710 2.17 1.94595 18.0 9.7411 −238.729 (Variable) 9.62 12 −14.788 0.60 1.48749 70.2 8.13 13 −22.5274.50 8.21 14 ∞ (Variable) 11.31 15* 7.500 3.13 1.55332 71.7 9.00 16*−67.550 1.00 8.33 17(SP) ∞ 1.00 7.59 18 12.503 0.60 1.84666 23.8 7.17 198.424 1.27 6.82 20 10.570 4.08 1.58144 40.8 6.74 21 −4.614 0.60 1.8061033.3 6.06 22 69.938 (Variable) 6.05 23 −17.595 0.70 1.77250 49.6 7.67 2446.227 (Variable) 8.03 25* 10.257 3.89 1.48749 70.2 11.13 26 −13.610(Variable) 11.23 27 ∞ 0.80 1.51633 64.1 20.00 28 ∞ 1.84 20.00 IP ∞Aspheric surface data 7th surface K = 2.79987e−001 A 4 = −5.35367e−005 A6 = −4.45027e−006 A 8 = 1.59055e−008 A10 = 1.04575e−009 15th surface K =−1.05117e−001 A 4 = 6.36084e−006 A 6 = −8.64819e−007 A 8 = 2.26861e−00816th surface K = −1.79154e+002 A 4 = 1.43988e−004 25th surface K =0.00000e+000 A 4 = −2.86643e−004 A 6 = 5.74087e−007 A 8 = −2.33846e−008Various data zoom ratio 15.03 Wide Middle Tele focal length 5.18 25.0077.84 F-number 3.07 4.33 5.72 Half angle of view (°) 33.59 7.83 2.53Image height 3.44 3.44 3.44 Total lens length 80.30 83.31 88.34 BF 1.841.84 1.84 d 5 0.50 11.63 17.50 d11 9.71 1.54 0.80 d14 16.47 6.55 4.30d22 1.79 11.71 13.97 d24 7.29 2.43 8.71 d26 3.98 8.90 2.51 Entrancepupil 18.09 63.98 164.63 Exit pupil 252.96 −261.06 33.94 Front principalpoint 23.38 86.61 431.14 Rear principal point −3.34 −23.16 −76.01 Zoomlens unit data Front Rear Lens Start Focal Unit principal principal unitsurface length length point point 1 1 32.16 9.38 2.30 −3.59 2 6 −6.167.16 1.31 −3.84 3 12 −90.61 5.10 −0.79 −5.70 4 15 13.48 11.68 −4.04−9.41 5 23 −16.42 0.70 0.11 −0.28 6 25 12.67 3.89 1.19 −1.57 GB 27 ∞0.80 0.26 −0.26 Lens element data lens Start surface Focal length 1 1−59.11 2 2 45.68 3 4 36.19 4 6 −9.17 5 8 −7.35 6 10 10.88 7 12 −90.61 815 12.38 9 18 −32.71 10 20 6.13 11 21 −5.35 12 23 −16.42 13 25 12.67 1427 0.00

Numerical Example 3

Unit mm Surface data Surface Effective No. r d nd νd diameter  1 34.0921.10 1.84666 23.8 26.50  2 19.352 4.94 1.49700 81.5 23.60  3 245.6250.10 22.28  4 21.016 3.15 1.77250 49.6 21.39  5 103.274 (Variable) 20.94 6 86.233 1.05 1.84954 40.1 13.35  7* 6.606 3.12 9.44  8 −15.055 0.602.00000 40.0 9.19  9 12.951 0.10 9.19 10 12.063 2.16 1.94595 18.0 9.3811 −35.833 (Variable) 9.36 12 ∞ 4.96 11.31 13 −15.308 0.60 1.51633 64.17.42 14 −41.341 (Variable) 7.49 15* 7.569 2.96 1.55332 71.7 8.11 16*−24.486 1.00 7.63 17(SP) ∞ 1.00 6.80 18 10.632 0.60 1.84666 23.8 6.59 195.868 1.41 6.23 20 9.638 3.56 1.60342 38.0 6.83 21 −9.408 0.60 1.8061033.3 6.54 22 715.065 (Variable) 6.55 23 −30.828 0.70 1.77250 49.6 7.4824 19.534 (Variable) 7.68 25* 10.933 3.46 1.48749 70.2 11.39 26 −16.828(Variable) 11.34 27 ∞ 0.80 1.51633 64.1 20.00 28 ∞ 2.40 20.00 IP ∞Aspheric surface data 7th surface K = 4.95519e−001 A 4 = −1.74245e−004 A6 = −9.87660e−006 A 8 = 2.61017e−007 A10 = −1.56231e−008 15th surface K= −4.55464e−001 A 4 = −1.03451e−004 A 6 = −5.23921e−007 A 8 =−2.56549e−009 16th surface K = −1.42480e−001 A 4 = 1.02387e−004 25thsurface K = 0.00000e+000 A 4 = −1.56104e−004 A 6 = 1.29154e−007 A 8 =−8.67868e−009 Various data zoom ratio 15.10 Wide Middle Tele focallength 5.18 22.00 78.22 F-number 3.07 4.84 6.46 half angle of view (°)33.59 8.89 2.52 Image height 3.44 3.44 3.44 Total lens length 73.4981.72 88.34 BF 2.40 2.40 2.40 d 5 0.50 9.20 15.87 d11 5.28 4.80 4.80 d1413.95 2.68 0.30 d22 0.85 12.10 14.49 d24 6.72 3.77 10.57 d26 5.84 8.811.94 Entrance pupil 17.37 49.95 154.44 Exit pupil −96.21 −174.21 42.84Front principal point 22.28 69.21 383.94 Rear principal point −2.78−19.60 −75.82 Zoom lens unit data Front Rear Lens Start Focal Unitprincipal principal unit surface length length point point 1 1 29.619.29 2.60 −3.27 2 6 −6.25 7.03 0.99 −4.28 3 12 −47.45 5.56 4.72 −0.63 415 12.16 11.12 −0.59 −8.24 5 23 −15.39 0.70 0.24 −0.15 6 25 14.17 3.460.95 −1.47 GB 27 ∞ 0.80 0.26 −0.26 Lens element data lens Start surfaceFocal length 1 1 −54.74 2 2 41.96 3 4 33.59 4 6 −8.47 5 8 −6.89 6 109.75 7 13 −47.45 8 15 10.80 9 18 −16.42 10 20 8.49 11 21 −11.52 12 23−15.39 13 25 14.17 14 27 0.00

Numerical Example 4

Unit mm Surface data Surface Effective No. r d nd νd diameter  1 60.2691.10 1.84666 23.8 27.53  2 26.489 5.05 1.49700 81.5 26.22  3 −76.7550.10 26.09  4 21.031 3.33 1.77250 49.6 23.09  5 75.809 (Variable) 22.45 6* −46.672 1.05 1.85135 40.1 12.32  7* 13.268 2.42 8.86  8 −8.325 0.601.88300 40.8 8.24  9 8.584 0.10 8.11 10 9.151 1.90 1.94595 18.0 8.16 11−84.808 (Variable) 8.13 12 ∞ (Variable) 11.31 13* 6.467 4.00 1.5163364.1 7.27 14* −21.838 1.00 6.41 15(SP) ∞ 1.00 5.67 16 89.305 0.601.85026 32.3 5.56 17 6.084 1.09 5.43 18 7.546 3.64 1.51742 52.4 6.30 19−7.668 0.60 1.88300 40.8 6.56 20* −22.132 (Variable) 6.86 21* 19.3122.83 1.48749 70.2 10.24 22 −43.947 (Variable) 10.10 23 ∞ 0.80 1.5163364.1 20.00 24 ∞ 4.89 20.00 IP ∞ Aspheric surface data 6th surface K =0.00000e+000 A 4 = 2.27484e−004 A 6 = 1.69367e−005 A 8 = −3.96934e−007A10 = 3.67104e−009 7th surface K = −1.79858e+000 A 4 = 1.66303e−004 A 6= 2.60989e−005 A 8 = 3.77154e−008 A10 = 1.84548e−008 13th surface K =−5.56364e−001 A 4 = −5.59307e−005 A 6 = 6.34812e−007 A 8 = −1.11004e−00814th surface K = 0.00000e+000 A 4 = 1.38992e−004 20th surface K =−4.82233e+000 A 4 = 3.65336e−005 A 6 = 7.10381e−006 A 8 = −3.92807e−007A10 = 1.65954e−008 21st surface K = 0.00000e+000 A 4 = 6.02068e−005 A 6= −1.64175e−006 A 8 = 3.06501e−008 Various data zoom ratio 15.67 WideMiddle Tele focal length 5.73 22.00 89.77 F-number 3.50 4.59 5.49 Halfangle of view (°) 31.43 9.04 2.23 Image height 3.50 3.50 3.50 Total lenslength 71.65 80.06 86.60 BF 4.89 4.89 4.89 d 5 0.50 10.50 17.50 d11 6.755.10 4.80 d12 17.21 6.55 4.30 d20 5.79 6.60 23.79 d22 5.29 15.21 0.10d24 4.89 4.89 4.89 Entrance pupil 16.81 57.16 230.25 Exit pupil −27.17−39.61 477.85 Front principal point 21.51 68.29 337.06 rear principalpoint −0.83 −17.11 −84.88 Zoom lens unit data Front Rear Lens StartFocal Unit principal principal unit surface length length point point 11 29.06 9.58 3.22 −2.74 2 6 −5.25 6.08 1.51 −2.71 MR 12 ∞ 0.00 0.00−0.00 3 13 16.98 11.93 −2.90 −10.75 4 21 27.93 2.83 0.59 −1.34 GB 23 ∞0.80 0.26 −0.26 Lens element data lens Start surface Focal length 1 1−56.67 2 2 40.28 3 4 36.70 4 6 −12.04 5 8 −4.71 6 10 8.82 7 13 10.15 816 −7.70 9 18 8.00 10 19 −13.55 11 21 27.93 12 23 0.00

Numerical Example 5

Unit mm Surface data Surface Effective No. r d nd νd diameter  1 40.1151.10 1.84666 23.8 27.50  2 22.601 5.01 1.49700 81.5 24.86  3 −639.469(Variable) 24.29  4 22.411 3.31 1.77250 49.6 23.18  5 96.137 (Variable)22.69  6 121.669 1.05 1.84954 40.1 13.43  7* 8.387 3.09 10.13  8 −13.0330.60 1.88300 40.8 9.44  9 8.611 0.10 9.08 10 9.163 2.11 1.94595 18.09.09 11 293.593 4.80 9.00 12 ∞ (Variable) 11.31 13* 7.266 3.67 1.5533271.7 8.20 14* −530.318 1.00 7.18 15(SP) ∞ 1.00 6.53 16 9.580 0.601.84666 23.8 6.37 17 5.742 1.45 6.03 18 10.456 3.47 1.56732 42.8 6.45 19−9.352 0.60 1.80610 33.3 6.47 20 −35.445 (Variable) 6.58 21 −15.120 0.701.77250 49.6 6.99 22 118.961 (Variable) 7.26 23* 12.808 3.49 1.4874970.2 11.80 24 −18.982 (Variable) 11.77 25 ∞ 0.80 1.51633 64.1 20.00 26 ∞2.22 20.00 IP ∞ Aspheric surface data 7th surface K = 2.50717e−002 A 4 =−1.20472e−006 A 6 = −6.57466e−006 A 8 = 3.87504e−007 A10 = −9.80177e−00913th surface K = −3.62944e−001 A 4 = −9.47829e−005 A 6 = −1.02524e−006 A8 = −1.04732e−008 14th surface K = 0.00000e+000 A 4 = −9.61549e−007 23rdsurface K = 0.00000e+000 A 4 = −9.18726e−005 A 6 = 4.92067e−007 A 8 =−1.16408e−008 Various data zoom ratio 16.00 Wide Middle Tele Focallength 5.41 23.69 86.55 F-number 3.07 4.43 5.75 Half angle of view (°)32.53 8.29 2.28 Image height 3.45 3.45 3.45 Total lens length 71.5282.05 88.34 BF 2.22 2.22 2.22 d 3 0.45 0.80 0.91 d 5 0.60 10.84 17.14d12 21.31 7.45 4.30 d20 5.69 8.24 6.56 d22 1.00 5.97 17.13 d24 2.30 8.582.13 Entrance pupil 18.78 63.41 196.24 Exit pupil −25.37 −204.08 40.49Front principal point 23.13 84.38 478.51 Rear principal point −3.19−21.47 −84.34 Zoom lens unit data Front Rear Lens Start Focal Unitprincipal principal unit surface length length point point 1 1 151.936.11 −0.93 −4.88 2 4 37.10 3.31 −0.56 −2.39 3 6 −5.50 11.75 1.73 −7.92 413 13.72 11.79 0.67 −8.62 5 21 −17.33 0.70 0.04 −0.35 6 23 16.27 3.490.98 −1.45 GB 25 ∞ 0.80 0.26 −0.26 Lens element data lens Start surfaceFocal length 1 1 −62.96 2 2 44.03 3 4 37.10 4 6 −10.65 5 8 −5.80 6 109.96 7 13 12.99 8 16 −18.24 9 18 9.29 10 19 −15.92 11 21 −17.33 12 2316.27 13 25 0.00

TABLE 1 Condition (1) (2) (3) (4) (5) (6) Numerical 1 12.2 1.02 0.221.87 1.67 0 Example 2 12.6 0.92 0.16 1.87 2.19 0 3 12.5 1.02 0.18 1.922.21 0 4 17.1 1.10 0.31 1.87 5.47 0 5 15.7 1.01 0.19 1.87 2.92 10

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2012-194001, filed Sep. 4, 2012, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. A zoom lens for an image pickup apparatus, thezoom lens comprising in order from an object side to an image side: afront unit including a first lens unit having a positive refractivepower and a second lens unit having a positive or negative refractivepower; a reflective mirror which bends an optical path from the frontunit; and a rear unit including two or more lens units, wherein: duringzooming, the reflective mirror is not moved, and the first lens unit andat least two lens units included in the two or more lens units of therear unit are moved in directions of optical axes of the front and rearunits, respectively; and when the zoom lens is retracted into a body ofthe image pickup apparatus, at least one of (a) rotation of thereflective mirror such that a normal line to a reflective surface of thereflective mirror is brought closer to parallel to the optical axis ofthe rear unit and (b) axial movement of the reflective mirror in thedirection of the optical axis of the rear unit is performed, and atleast part of the front unit is moved into a space formed by the atleast one of the rotation and the axial movement of the reflectivemirror, and wherein the following conditions are satisfied:10.5<ft/|fn|<30.00.80<(Lf−L)/Lm<1.30 where fn represents a focal length of a strongestnegative power lens unit having a negative refractive power whoseabsolute value is maximum among those lens units each having a negativerefractive power and included in the front unit, ft represents a focallength of the entire zoom lens at a telephoto end, Lm represents alength of the reflective mirror in a sectional plane including theoptical axes of the front and rear units, Lf represents a sum ofoptical-axis-directional thicknesses of respective lens units includedin the front unit, and L represents a shorter one of lengths in thedirection of the optical axis of the front unit from an apex of amost-object side lens surface of the first lens unit to ends of thereflective mirror in the sectional plane after the zoom lens isretracted in the body of the image pickup apparatus.
 2. A zoom lensaccording to claim 1, wherein the following condition is satisfied:0.10<fr/ft<0.40 where fr represents a focal length of a most-image sidelens unit disposed at a most-image side position among the lens unitsincluded in the rear unit.
 3. A zoom lens according to claim 1, whereinthe strongest negative power lens unit in the front unit includes two ormore negative lenses, and the following condition is satisfied:1.85<Nn<2.00 where Nn represents an average refractive index ofmaterials of the two or more negative lenses.
 4. A zoom lens accordingto claim 1, wherein one lens unit included in the rear unit comprises inorder from the object side to the image side: a first sub-lens unit; anda second sub-lens unit which is moved in a direction including avertical direction component to the optical axis of the rear unit forcorrecting image blur due to shaking of the zoom lens.
 5. A zoom lensaccording to claim 1, wherein the following condition is satisfied:1.50<Zf/Zr<6.00 where Zf represents a variable magnification ratio ofthe front unit, and Zr represents a variable magnification ratio of therear unit.
 6. A zoom lens according to claim 1, wherein the followingcondition is satisfied:|α|<15° where α represents an angle formed between the normal line ofthe reflective surface of the reflective mirror and the optical axis ofthe rear unit after the zoom lens is retracted in the body of the imagepickup apparatus.
 7. A zoom lens according to claim 1, wherein, when thezoom lens is retracted into the body of the image pickup apparatus, boththe rotation and the axial movement of the reflective mirror areperformed.
 8. A zoom lens according to claim 1, wherein the front unitcomprises in order from the object side to the image side: the firstlens unit; and the second lens unit having the negative refractivepower, and wherein the rear unit comprises in order from the object sideto the image side: a third lens unit having a positive refractive power;a fourth lens unit having a negative refractive power; and a fifth lensunit having a positive refractive power.
 9. A zoom lens according toclaim 1, wherein the front unit comprises in order from the object sideto the image side: the first lens unit; the second lens unit having thenegative refractive power; and a third lens unit having a negativerefractive power, and wherein the rear unit comprises in order from theobject side to the image side: a fourth lens unit having a positiverefractive power; a fifth lens unit having a negative refractive power;and a sixth lens unit having a positive refractive power.
 10. A zoomlens according to claim 1, wherein the front unit comprises in orderfrom the object side to the image side: the first lens unit; and thesecond lens unit having the negative refractive power, and wherein therear unit comprises in order from the object side to the image side: athird lens unit having a negative refractive power; a fourth lens unithaving a positive refractive power; a fifth lens unit having a negativerefractive power; and a sixth lens unit having a positive refractivepower.
 11. A zoom lens according to claim 1, wherein the front unitcomprises in order from the object side to the image side: the firstlens unit; and the second lens unit having the negative refractivepower, and wherein the rear unit comprises in order from the object sideto the image side: a third lens unit having a positive refractive power;and a fourth lens unit having a positive refractive power.
 12. A zoomlens according to claim 1, wherein the front unit comprises in orderfrom the object side to the image side: the first lens unit; the secondlens unit having the positive refractive power; and a third lens unithaving a negative refractive power, and wherein the rear unit comprisesin order from the object side to the image side: a fourth lens unithaving a positive refractive power; a fifth lens unit having a negativerefractive power; and a sixth lens unit having a positive refractivepower.
 13. An image pickup apparatus comprising: a body of the imagepickup apparatus; a zoom lens; and an image sensor which receives animage formed by the zoom lens, wherein the zoom lens comprising in orderfrom an object side to an image side: a front unit including a firstlens unit having a positive refractive power and a second lens unithaving a positive or negative refractive power; a reflective mirrorwhich bends an optical path from the front unit; and a rear unitincluding two or more lens units, wherein: during zooming, thereflective mirror is not moved, and the first lens unit and at least twolens units included in the two or more lens units of the rear unit aremoved in directions of optical axes of the front and rear units,respectively; and when the zoom lens is retracted into the body of theimage pickup apparatus, at least one of (a) rotation of the reflectivemirror such that a normal line to a reflective surface of the reflectivemirror is brought closer to parallel to the optical axis of the rearunit and (b) axial movement of the reflective mirror in the direction ofthe optical axis of the rear unit is performed, and at least part of thefront unit is moved into a space formed by the at least one of therotation and the axial movement of the reflective mirror, and whereinthe following conditions are satisfied:10.5<ft/|fn|<30.00.80<(Lf−L)/Lm<1.30 where fn represents a focal length of a strongestnegative power lens unit having a negative refractive power whoseabsolute value is maximum among those lens units each having a negativerefractive power and included in the front unit, ft represents a focallength of the entire zoom lens at a telephoto end, Lm represents alength of the reflective mirror in a sectional plane including theoptical axes of the front and rear units, Lf represents a sum ofoptical-axis-directional thicknesses of respective lens units includedin the front unit, and L represents a shorter one of lengths in thedirection of the optical axis of the front unit from an apex of amost-object side lens surface of the first lens unit to ends of thereflective mirror in the sectional plane after the zoom lens isretracted in the body of the image pickup apparatus.